Emulsions generally refer to heterogeneous systems that comprise two immiscible liquids. In agriculture, emulsions provide formulation vehicles for delivery of herbicides, insecticides, fungicides, bactericides, and fertilizers.
Mechanical agitation, such as shaking or stirring, or another energy input is required to form an emulsion. Emulsions are inherently unstable, meaning that once they are formed, the immiscible liquids tend to revert or separate. Emulsifying agents, such as surface-active agents, can be used to increase the stability of the emulsions. In the context of emulsions, “stable” or “stability” means that the droplet particles of one liquid are uniformly distributed into another liquid and that this status is maintained for a desirable amount of time.
Emulsions are especially useful in the field of agriculture wherein numerous lipophilic active ingredients must be dissolved and suspended into water prior to application to the plants. An oil-in-water emulsion (O/W emulsion) is an emulsion wherein liquid oil droplets are finely dispersed in water. Preparing stable O/W emulsions in very difficult and frequently involves extensive experimentation to determine formulations that provide stable concentrated products for end-use diluted emulsions.
The emulsion system plays an essential role in providing stable emulsions, but identification of a proper system is complex and not easy to identify because of the required optimization of many different formulation characteristics, such as interfacial tension, viscosity, relative density, and temperature.
In addition, there are hundreds of different emulsifiers and surfactants commercially available with vastly different properties. The available emulsifiers and surfactants could be used in formulations in varying combinations and amounts to produce thousands of different potential formulations, each producing unpredictable stability characteristics. When more than one emulsifier or surfactant are combined in a formulation, they produce an emulsion system.
Calsogen® EH (available from Clariant) is an emulsifier, specifically, an iso-C12 alkyl benzene sulphonate calcium salt.
Surfonic® CO 36 (available from Huntsman, Inc.) is a surfactant and it contains polyglycol esters of castor oil.
Cinnamaldehyde is a naturally occurring organic compound that can be derived from the bark of trees of the genus Cinnamomum. Cinnamaldehyde is a viscous oil that has low solubility in water. Cinnamaldehyde does not present any known risk to humans or the environment and is considered to have a minimal safety risk. For this reason, it is not regulated by the Environmental Protection Agency (“EPA”) because it is exempt from the Federal Insecticide, Fungicide, and Rodenticide Act (“FIFRA”). See 40 C.F.R. §152.25(f).
Cinnamaldehyde is known to have pesticidal activity. For example, cinnamaldehyde is effective against nematodes. See, for example, U.S. Pat. No. 6,251,951 B1.
Diallyl disulfide (4,5-dithia-1,7-octadiene) is a naturally occurring organosulfur compound that can be derived from garlic and plants of the genus Allium. Diallyl disulfide is an oil that has low solubility in water. Diallyl disulfide does not present any known risk to humans or the environment and is considered to have a minimal safety risk. For this reason, it is not regulated by the Environmental Protection Agency (“EPA”) because it is exempt from the Federal Insecticide, Fungicide, and Rodenticide Act (“FIFRA”). See 40 C.F.R. §152.25(f).
There is a need to improve the safety characteristics of pesticides that are applied to plants intended for human and animal consumption. In order to achieve the goal of providing a safer pesticide, users must: (1) use environmentally safe actives, such as essential oils; and (2) if using essential oils, then they must include an environmentally safe emulsion system.
In prior art formulations, the use of environmentally harmful organic, solvents or other components were required to produce stable and effective dilutable emulsions if they contained plant essential oils, such as cinnamaldehyde and dially disulfide. Although organic solvents are very effective in forming emulsions, they are also often flammable, corrosive or toxic to living systems and are of environmental concern. For example, ProGuard® 30% is a commercially available insecticide, miticide and fungicide that contains cinnamaldehyde. However, ProGuard® 30% also contains the undesirable ingredient o-Phenylphenol.
Therefore, there is a need for environmentally safe pesticidal formulations that contain effective but safe actives.